Lubricant compositions



United States Patent Ofiice 3,228,879 Patented Jan. 11, 1966 3,228,879 LUBRICANT COMPOSITIONS Edwin L. De Young, Milwaukee, Wis., and Roger W.

Watson, Highland, Ind., assignors to Standard Oil Company, Chicago, 11]., a corporation of Indiana No Drawing. Filed Jan. 16, 1962, Ser. No. 167,223 6 Claims. (Cl. 252--46.3)

This invention relates to lubricant oil inhibited against silver wear tendencies by the incorporation therein of certain silicon-containing additives.

Many hydrocarbon lubricant oils are compounded with various sulfur-containing additives which serve as oxidation or corroison inhibitors. Sulfur compounds, particularly those of an organic nature, promote excess wear of silver and silver-containing bearings and bushings.

It has now been discovered, in accordance with the in vention, that excessive wear of silver bearings may be inhibited substantially by incorporating into hydrocarbon lubricant oils which normally tend to promote excess wear, a minor amount of the reaction product of silicon disulfide with a member of the group consisting of alkyl and aryl primary and secondary amines.

The resultant compositions are outstanding additives with respect to inhibiting excess silver wear. In some instances, wear reduction is as much as 95 percent, or even more. In addition, the additives herein described often act as oxidation inhibitors as well as silver wear inhibitors, thus permitting further benefits by reducing the quantity of sulfur-containing oxidation inhibitors used.

The additives employed according to the invention may be prepared simply by reacting a silicon d-isulfide with a primary or secondary amine under anhydrous conditions, advantageously while maintaining the temperature within the range of about 50 to 150 C., preferably about 90 to 120 C. A stoichiometric excess of amine is advantageously employed; unreactcd amine may be removed at the conclusion of reaction by distillation or other equivalent means.

It is believed (Malatesta, Gazz. Chirn. Ital., 78, 753- 63, 1948; Chemical Abstracts, 43, 4630, 1949) that the reaction product has the formula of a silicon atom linked through amine nitrogen atoms to four radicals which are the residues of the amine reactants. This is apparently the case whether the amine is primary or secondary, although the above-cited article indicates that the product compositions may vary somewhat depending upon the nature of the amine reactant. It has been found, however, that the conditions under which the additive is prepared do not appear to be critical; and irrespective of the precise structural formula, it appears that the only essential prerequisite of the additive is that it be prepared as broadly outlined above.

A wide variety of amines may be employed in preparing the present additives. As illustrative examples of such amines, there may be mentioned the unsubstituted alkyl amines such as methyl amine, ethyl amine, hexyl amine, dodecyl amine, hexadecyl amine, eicosyl amine; the unsubstituted secondary alkyl amines such as ethylsec-butyl amine and di-isopropyl amine; and aryl-substituted primary and secondary alkyl amines such as ethylbenzyl amine, benzyl amine, methylbenzyl amine; the aryl and alk-aryl amines such as aniline, methyl aniline, amyl aniline, dodecyl aniline; the cycloalkyl and alkylsubstituted cycloalkyl amines such as pyridine, piperidine, alpha-picoline, 3,5-lutidine, etc. The various diamines, such as ethylene diamine, tetramethylene diamine, pentamethylene diamine, etc. may also be employed; a portion of the reaction product with silicon disulfide may then have a cyclic structure formed when nitrogen atoms at the opposite ends of the same diamine molecule are attached to the same silicon atom.

An outstanding class of diamines are the N-alkyl alkylene diamines, such as the N-alkyl ethylene or propylene diamine in which the alkyl group contains from 12 to 22 carbon atoms, preferably from 12 to 18 carbon atoms. The N-alkyl alkylene diamines are commercially available as the diamines prepared from hydrogenated tallow fatty acids, coco fatty acids, and soy bean fatty acids, with the various fatty acids including myristic palmitic, stear-ic, oleic, capric, lauric, and linoleic groups.

Unless the contrary is clearly indicated, it is intended that the terms amine, primary amine and secondary amine denote the monoamines as well as the diamines and higher primary and secondary amines. Similarly, alkyl includes substituted alkyl, e.g. aralkyl; and by the same token, aryl includes substituted aryl, e.g. alkaryl.

The inventive additive may be incorporated into a wide variety of hydrocarbon lubricant oils. Such oils, virtually all of which may be improved with respect to their silver wear, characterized according to the invention may be any of the natural or synthetic hydrocarbon oils of suitable viscosity range e.g. from about 20 S.S.U. viscosity at F. to about 3000 S.S.U. at 210 F. These oils may be derived from natural, e.g. petroleum sources, or may be composed in whole or in part of synthetic hydrocarbons, as for example, the polybutenes and hydrogenated polybutenes. The oils may contain any of the ingredients normally incorporated for the purposes of improved detergency, oxidation resistance, lubricity, extreme pressure characteristics, rust inhibition, pour point, etc. Ordinarily it is considered that sulfur-containing ingredients, particularly the organo-sulfur compounds, commonly used to enhance oxidation or corrosion inhibiting properties are the worst ofienders with respect to silver wear tendencies. Typical sulfur-containing materials normally found in lubricant oils include the sulfurized terpenes, sulfurized tall or sperm oil, various reaction products of phosphorus pentasulfide with hydrocarbons, metal sulfonates, sulfonochlorated olefins, metal dithiophosphates, etc.

The inventive additives may be added to such hydrocarbon lubricant oils in a wide range of concentrations depending upon the intrinsic silver wear tendencies of the lubricant and on the extent of wear inhibition desired. Ordinarily the amount will range from as little as 0.05 wt. percent, but may be even less, to as much as 3 percent or even more. Simple testing by use of the Falex tester with a silver ball (the Falex test is described in Journ Inst. Pet, 32, April 1946), for determining the necessary concentration of the particular inhibitor needed to provide a desired improvement.

Illustrative embodiments of the invention are given in the following examples, which are provided for illustration only; hence they are not to be considered wholly definitive with respect to scope or conditions.

Example I This example illustrates the preparation and testing of a silver wear inhibitor prepared by reacting silicon disulfide with amyl aniline.

To a flask containing 65.2 g. (0.4 mole) of amyl aniline is added 4.6 g. (0.05 mole) of finely powdered silicon disulfide. The mixture is heated at 100110 C. for 3-4 hours, after which no further hydrogen sulfide evolution is observed.

The material is filtered and excess amine is removed by vacuum distillation.

The product is a low-melting brown solid analyzed 4.8 percent silicon.

To test its efliciency as a silver wear inhibitor, a rubricant oil is prepared from 73 viscosity index mineral base oil containing 2.8 wt. percent detergent (barium neutralized and hydrolyzed reaction product of phosphorus pentasulfide with a hydrocarbon), 1.0 percent calcium phenate and 0.2 percent sulfurized terpene.

When tested with a silver ball Falex tester, the above described lubricant causes a silver Weight loss of 275.0 mg. However, when only 0.5 Wt. percent of the silicon disulfide-amyl aniline reaction product is added, the weight loss under identical conditions is 38.4 and 50.4 for duplicate tests.

Example 11 In this example the conditions of Example I are repeated, except that arnyl aniline is replaced by respectively, aniline, piperidine, methyl piperidine, picoline, methyl amine, ethyl amine, diethyl amine, sec-butyl amine, N-hexyl amine, tetramethylene diamine, and the ethylene diamine product derived from tallow fatty acids (Armour Chemical Divisions Duomeen T). In each instance, excellent silver wear inhibition is demonstrated under the conditions of the silver ball Falex test.

Example 111 This example illustrates the preparation of an unsubstituted alkyl arrnine silicon disulfide reaction product.

To a flask containing 62.8 g. (0.4 mole) of dodecyl amine is added 4.6 g. (0.05 mole) of silicon disulfide The mixture is stirred at IOU-110 C. for 3-4 hours, after which hydrogen sulfide evolution ceases. is filtered and excess amine is removed by vacuum distillation. The product is a low-melting brown solid, which analyzed 0.98 percent silicon.

When tested under the conditions of the silver ball Falex test, and utilizing the same oil as described for Example I, silver weight loss is only 12.0 and 15.2 mg. in duplicate tests, in contrast to the 275.0 mg. for the control.

Example IV This example illustrates the preparation of an example of the invention wherein the amine reactant is the diamine prepared from hydrogenated tallow fatty acids, or mixtures of myristic, palmitic, stearic, and oleic groups predominating in stearic and palmitic groups.

To a flask containing 64 g. (an estimated 0.2 mole) of Armour Chemical Divisions Duomeen T is added 4.0 g. silicon disulfide. The mixture is heated to 100110 C. for 6 hours, after which the mixture is filtered and excess amine evaporated off under vacuum.

The product contains 4.4 percent silicon (3.15 calculated.

The material When tested under the silver ball Falex test, in the oil described for Example I, silver weight loss is 91.2 and 71.7 mg. in duplicate tests in comparison with 275 mg. for the uninhibited oils.

Thus it is apparent that there has been provided in accordance with the invention an outstanding class of silver wear inhibitors. The reaction product of silicon disulfide with any primary or secondary amine containing only hydrogen and carbon substituents and preferably of no more than 20 carbon atoms per amine molecule is thus an excellent additive.

Although the invention has been described in conjunction with certain specific embodiments, it will be evident to those skilled in the art that various alternatives, modifications, and variations will be manifest, in light of the fore-going descriptions. Hence it is intended to include all such alternatives, modifications and variations as fully within the spirit and broad scope of the appended claims.

We claim:

1. A hydrocarbon lubricating oil containing a sulfurcontaining additive normally causing excessive silver wear, and a minor amount sufficient to inhibit such wear of the reaction product obtained by reacting silicon di sulfide and an amount of an amine in excess of the sto-ichiometric proportion of amine to silicon disulfide, said amine being a member of the group consisting of primary and secondary amines having from 2 to 20 carbon atoms per molecule, at a temperature of from about to about C. until the evolution of hydrogen sulfide ceases, and thereafter removing unreacted amine from the reaction product.

2. The lubricating oil of claim 1 wherein said amine is a primary alkyl amine.

3. The lubricating oil of claim 1 wherein said amine is N-alkyl propylene diamine.

4. The lubricating oil of claim 1 wherein said amine is dodecyl amine.

5. The lubricating oil of claim 1 wherein said amine is an aryl amine.

6. The lubricating oil of claim 1 wherein said amine is a-myl aniline.

References Cited by the Examiner UNITED STATES PATENTS 2,807,635 9/ 1957 Breederveld et al. 25249.6 X 2,876,209 3/1959 B'enneville et al. 252463 X DANIEL L. WYMAN, Primary Examiner.

ALPHONSO D. SULLIVAN, Examiner. 

1. A HYDROCARBON LUBRICATING OIL CONTAINING A SULFURCONTAINING ADDITIVE NORMALLY CAUSING EXCESSIVE SILVER WEAR, AND A MINOR AMOUNT SUFFICIENT TO INHIBIT SUCH WEAR OF THE REACTION PRODUCT OBTAINED BY REACTING SILICON DISULFIDE AND AN AMOUNT OF AN AMINE IN EXCESS OF THE STOICHIOMETRIC PROPORTION OF AMINE TO SILICON DISULFIDE, SAID AMINE BEING A MEMBER OF THE GROUP CONSISTING OF PRIMARY AND SECONDARY AMINES HAVING FROM 2 TO 20 CARBON ATOMS PER MOLECULE, AT A TEMPERATURE OF FROM ABOUT 50 TO ABOUT 150*C. UNTIL THE EVOLUTION OF HYDROGEN SULFIDE CEASES, AND THEREAFTER REMOVING UNREACTED AMINE FROM THE REACTION PRODUCT. 